Blockchain-based cross-chain data access method and apparatus

1. A computer-implemented method for blockchain-based cross-chain data access, the computer-implemented method comprising: receiving, from a node of a first blockchain of a multi-chain system comprising a plurality of different blockchains and including the first blockchain and a target blockchain, an access request for accessing target data stored in a target node of the target blockchain, wherein the access request comprises an indication of the target blockchain that stores the target data and an access path in the multi-chain system to the target data, wherein the access path comprises immutable content stored by an access path node of the target blockchain, wherein the immutable content is used as an address for accessing the access path node, wherein the access path node comprises an access link that corresponds to the target data, wherein the access link is used to point to the target node from the access path node, and wherein the access path further comprises an instance name of an instance of the target blockchain supporting a blockchain protocol; obtaining the target data from the target blockchain based on the access path; and transmitting the target data to the node of the first blockchain.

2. The computer-implemented method of claim 1 , wherein: the access path is in a data format of a multi-layer structure; and the computer-implemented method further comprises: recording, with a data node domain field of the access path, area information corresponding to the access path node accessing the target data, wherein the area information comprises identification information of the target blockchain; recording, with a data node identifier field of the access path, identification information of the access path node; and recording, with a data node path field of the access path, access path information of the target data traversed and identified starting from the access path node.

3. The computer-implemented method of claim 2 , wherein the data node domain field further comprises a protocol field and an instance field; and the method further comprises: recording, with the protocol field, a protocol name of the blockchain protocol supported by the target blockchain; and recording, with the instance field, the instance name of the instance of the target blockchain supporting the blockchain protocol.

4. The computer-implemented method of claim 3 , wherein the data node domain field further comprises a retrieval space field; and the method further comprises: recording, with the retrieval space field, identification information of data retrieval space used when the identification information of the access path node is used as a query index to query the target data on the target blockchain.

5. The computer-implemented method of claim 4 , wherein a content format corresponding to the access link is in the data format of the multi-layer structure.

6. The computer-implemented method of claim 5 , wherein the data node path field of the access link further comprises a link field and an attribute field; and the method further comprises: recording, with the link field, a name of the access link; and recording, with the attribute field, attribute information of the target data, wherein the attribute information is used as a retrieval keyword to retrieve the target data.

7. The computer-implemented method of claim 1 , wherein the multi-chain system comprises a blockchain system consisting of a main chain and a plurality of subchains corresponding to the main chain.

8. A non-transitory, computer-readable medium storing one or more instructions executable by a computer system to perform operations comprising: receiving, from a node of a first blockchain of a multi-chain system comprising a plurality of different blockchains and including the first blockchain and a target blockchain, an access request for accessing target data stored in a target node of the target blockchain, wherein the access request comprises an indication of the target blockchain that stores the target data and an access path in the multi-chain system to the target data, wherein the access path comprises immutable content stored by an access path node of the target blockchain, wherein the immutable content is used as an address for accessing the access path node, wherein the access path node comprises an access link that corresponds to the target data, wherein the access link is used to point to the target node from the access path node, and wherein the access path further comprises an instance name of an instance of the target blockchain supporting a blockchain protocol; obtaining the target data from the target blockchain based on the access path; and transmitting the target data to the node of the first blockchain.

9. The non-transitory, computer-readable medium of claim 8 , wherein: the access path is in a data format of a multi-layer structure; and the operations further comprise: recording, with a data node domain field of the access path, area information corresponding to the access path node accessing the target data, wherein the area information comprises identification information of the target blockchain; recording, with a data node identifier field of the access path, identification information of the access path node; and recording, with a data node path field of the access path, access path information of the target data traversed and identified starting from the access path node.

10. The non-transitory, computer-readable medium of claim 9 , wherein the data node domain field further comprises a protocol field and an instance field; and the operations further comprise: recording, with the protocol field, a protocol name of the blockchain protocol supported by the target blockchain; and recording, with the instance field, the instance name of the instance of the target blockchain supporting the blockchain protocol.

11. The non-transitory, computer-readable medium of claim 10 , wherein the data node domain field further comprises a retrieval space field; and the operations further comprise: recording, with the retrieval space field, identification information of data retrieval space used when the identification information of the access path node is used as a query index to query the target data on the target blockchain.

12. The non-transitory, computer-readable medium of claim 11 , wherein a content format corresponding to the access link is in the data format of the multi-layer structure.

13. The non-transitory, computer-readable medium of claim 12 , wherein the data node path field of the access link further comprises a link field and an attribute field; and the operations further comprise: recording, with the link field, a name of the access link; and recording, with the attribute field, attribute information of the target data, wherein the attribute information is used as a retrieval keyword to retrieve the target data.

14. The non-transitory, computer-readable medium of claim 8 , wherein the multi- chain system comprises a blockchain system consisting of a main chain and a plurality of subchains corresponding to the main chain.

15. A computer-implemented system, comprising: one or more computers; and one or more computer memory devices interoperably coupled with the one or more computers and having tangible, non-transitory, machine-readable media storing one or more instructions that, when executed by the one or more computers, perform one or more operations comprising: receiving, from a node of a first blockchain of a multi-chain system comprising a plurality of different blockchains and including the first blockchain and a target blockchain, an access request for accessing target data stored in a target node of the target blockchain, wherein the access request comprises an indication of the target blockchain that stores the target data and an access path in the multi-chain system to the target data, wherein the access path comprises immutable content stored by an access path node of the target blockchain, wherein the immutable content is used as an address for accessing the access path node, wherein the access path node comprises an access link that corresponds to the target data, wherein the access link is used to point to the target node from the access path node, and wherein the access path further comprises an instance name of an instance of the target blockchain supporting a blockchain protocol; obtaining the target data from the target blockchain based on the access path; and transmitting the target data to the node of the first blockchain.

16. The computer-implemented system of claim 15 , wherein: the access path is in a data format of a multi-layer structure; and the operations further comprise: recording, with a data node domain field of the access path, area information corresponding to the access path node accessing the target data, wherein the area information comprises identification information of the target blockchain; recording, with a data node identifier field of the access path, identification information of the access path node; and recording, with a data node path field of the access path, access path information of the target data traversed and identified starting from the access path node.

17. The computer-implemented system of claim 16 , wherein the data node domain field further comprises a protocol field and an instance field; and the operations further comprise: recording, with the protocol field, a protocol name of the blockchain protocol supported by the target blockchain; and recording, with the instance field, the instance name of the instance of the target blockchain supporting the blockchain protocol.

18. The computer-implemented system of claim 17 , wherein the data node domain field further comprises a retrieval space field; and the operations further comprise: recording, with the retrieval space field, identification information of data retrieval space used when the identification information of the access path node is used as a query index to query the target data on the target blockchain.

19. The computer-implemented system of claim 18 , wherein a content format corresponding to the access link is in the data format of the multi-layer structure.

20. The computer-implemented system of claim 19 , wherein the data node path field of the access link further comprises a link field and an attribute field; and the operations further comprise: recording, with the link field, a name of the access link; and recording, with the attribute field, attribute information of the target data, wherein the attribute information is used as a retrieval keyword to retrieve the target data.